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Ketones in urine (ketonuria)
Products of fat breakdown. They appear when the body is forced to take energy from fat instead of glucose.
Other names: KET, Ketones, acetone in urineSection: UrinalysisSpecialist: Primary care physician, endocrinologist, pediatrician; in pregnancy — an obstetrician-gynecologistSample: UrinePart of: Urinalysis
Updated: September 17, 2026·MedProtect editorial team Reference information — not a diagnosis or a prescription
In shortNormally there are no ketones in urine. They appear when the body switches to fat breakdown: fasting, strict diets, vomiting, morning sickness. In people with diabetes, urinary ketones signal insulin shortage and the risk of ketoacidosis.
What this marker is
Ketone bodies (often called “acetone” on reports) form in the liver when fats are broken down. A small amount is excreted unnoticed, but with massive fat breakdown ketones accumulate — this is ketonuria.
The cause is always the same — cells lack glucose: either too little comes with food (fasting, keto diet), or it cannot be absorbed without insulin (diabetes). In children ketonuria develops quickly — with vomiting, fever and food refusal.
Reference ranges
Group
Reference range
All groups
normally absent (negative)
Traces (+)
fasting over 12–14 hours, low-carb diet — retest after eating
Marked ketonuria (++, +++)
in diabetes — risk of ketoacidosis: check blood sugar urgently
Occasional ketone traces after a long food gap or workout are common. Ketonuria with high blood sugar is dangerous: a sign of approaching ketoacidosis that needs urgent care. Ranges differ between laboratories.
Check your value
Enter the number from your lab report — see how it compares with the typical range. Mind the units shown in the chosen row.
An approximate comparison with a typical range, not a diagnosis. Ranges differ between laboratories — use the one on your report; a doctor interprets the result.
When it is high or appears: possible causes
Fasting and strict dietsA long food gap, keto diet — ketones clear after carbohydrates.
Diabetes mellitusInsulin shortage — ketones with high blood sugar: ketoacidosis risk.
Vomiting and morning sicknessFluid loss and inability to eat — fast onset in children and pregnancy.
Fever and infectionsFaster metabolism and food refusal.
AlcoholHeavy drinking without food — alcoholic ketoacidosis.
What can skew the result
These factors can shift the result without any disease — keep them in mind before a retest:
Fasting over 12 hoursLow-carb and keto dietsHard workoutVomiting before the test
How to prepare
A midstream sample of the first morning urine after cleaning the genital area, in a clean container, delivered to the lab within 1–2 hours. Details: Preparation: urine.
When a retest makes sense
A doubtful result is retested in 1–2 weeks with careful preparation. During treatment of a urinary tract infection, a follow-up is done 1–2 weeks after the course, as prescribed by the doctor.
Who usually reviews this result
An out-of-range result is usually reviewed by: Primary care physician, endocrinologist, pediatrician; in pregnancy — an obstetrician-gynecologist. Bring your report and any previous results to the visit.
Names used on lab reports
Look for one of these names on your report: Ketones in urineKETKetonesAcetone in urineKetonuria
Several markers on your report?
The app reads your whole report — this marker together with its neighbors, not one by one.
The usual cause is vomiting, fever or a long food gap. Feed the child, give a sweet drink and retest in a few hours. If ketones persist, the child is listless or vomiting continues — see the pediatrician; IV fluids are sometimes needed.
Ketones in diabetes — how dangerous?
Urine ketones with high blood sugar signal insulin shortage and approaching ketoacidosis, an emergency. Check blood sugar immediately; from 13–14 mmol/L with ketones, contact the doctor or call an ambulance.
I am on a keto diet and have urinary ketones — normal?
Yes, on a strict low-carb diet ketonuria is expected — that is how this diet works. Drink enough fluids and see a doctor if you feel unwell.
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